1) Hi, I will be explaining here how to mix images.
Your output should look something like this by the end of this tutorial.
Image Mixing-Final Output
First Choose 3 images,1 for the Dune, second for the Clouds and the 3rd for the Building.
3 Images
2) Second step is to select the building.You can use the pen tool.Pen tool, as i'm sure you know, is a tool which is used to create shapes and various styles of graphics.Here, I am using it for selcection.I feel that once you have experience of selecting an object with the pen tool, it is the best selection tool.
Select the whole building and then press Ctl + Enter to select the outline area. Now take a copy(Ctl+C).
Select Building using Pen Tool
3) After that choose the second image(Dune).Then follow the same procedure as explained above.
Or an easier way would be to use the Eraser tool to erase the clouds. Just make sure you erase well. Erase Clouds using Eraser Tool 4) Paste your copied image into this image. The layer should be on top of the dune layer. Refer to the image below:
Building and Dune
4)After that, place the image of the cloud. See the image below to find out what your final output will look like!
Image Mixing-Final Output
* Please note that your layer arrangement should be like this Sky>Dune>Building.
Layer Arrangement
Well, now you have successfully mixed three different kinds of images to make a beautiful image!